-Fins made of your cardboard
-Garbage bag for Parachute
Step 2: Build the Rocket Body
To build the rocket body you must use a 1 liter bottle where you would be able to apply the fins or whatever is necessary. The main bottle you should not cut at all because that is where the full aka water is going to be stored.
Step 3: Construct Fins
Grab a cardboard box and flatten it so that you will have more access to draw out you fins. Once your fins are drawn out you should cut out those drawings and then apply the now fins to the main base bottle with tape duct tape preferably.
Step 4: Construct Parachute
The parachute you want depends on the size of the garbage bag. First cut the seams of the garbage bag so the the garbage bag will open and is flat. Now get some type of marker and draw a prefect circle then cut it out. Then have about 8 strings perfectly the same size the hole punch 8 holes in the garbage bag and now put the strings through each one and tape them down.
Step 5: Cone Nose
To make a cone you must have a power drill that you can attach a bottle too and have some sort of heating device. Start rotating the bottle so that the heat evenly starts to melt the bottom of the bottle in to a pointed circle. After it cools down you need to cut the bottle to your desired length so that it fits easily with the base bottle.
Step 6: Final Step
Once you have finished all the steps you must now put everything together the parachute should be folded not stuffed in the cone so that the parachute can deploy at the rockets peak. Its best if you use some type of lubricant to loosen up the nose cone.